The present invention relates to a vibration damper for a clutch and more particularly to a damper for a lock-up clutch in a hydrodynamic device.
The use of a combination spring and friction type vibration damper in a conventional clutch ahead of a manually operated transmission for the purpose of neutralizing torsional vibrations emanating from the engine which would otherwise cause disturbing noises in the transmission and driveline is well known.
With an automatic transmission employing a constant slipping device such as a fluid coupling or a torque converter, the torsional vibrations are efficiently absorbed hydraulically and a vibration damper has been found unnecessary.
More recently, however, in order to obtain better fuel economy from motor vehicles employing automatic transmissions, a fluid coupling or a torque converter utilizes a lock-up clutch which at a programmed vehicle speed depending upon load and acceleration locks up the coupling or torque converter so that slippage no longer occurs. This usually takes place after the transmission is in high gear. Thus, when locked up, torsional vibrations from the engine can not be absorbed hydraulically and, therefore, manifest themselves in a disturbing manner such that a vibration damper in the lock-up clutch plate is necessary to eliminate the disturbance.
The present invention relates to an improved torsional vibration damper for a lock-up clutch utilized with a torque converter in an automotive vehicle. The vibration damper has a high torque capacity and angular displacement but will fit into a very limited space adjacent the torque converter shell. The lock-up clutch in the torque converter assembly provides a direct drive between the engine and transmission of the vehicle, thereby eliminting the slip of the torque converter and resulting loss of economy. Many of the prior vibration dampers used in a torque converter environment lacked the torque capacity to do the job and fit in the space available.
To provide the necessary torque capacity and angular displacement, larger springs were utilized on a slightly greater radius in the damper which required more of the limited space available. To utilize these larger springs, drive plates for the vibration damper were designed having peripheries with alternate legs and spaces so that all the legs of both plates are attached to the common plane of the piston member for the lock-up clutch. The legs of each drive plate provide radial mounting flanges which alternate on a single circle to be attached to the clutch piston member.
In view of the larger springs located on a greater than normal radius, the outermost window lip of the front drive plate was eliminated, and the limit stop means between the drive plates and the flange extending from the hub of the vibration damper is omitted for greater simplicity of assembly of the damper.
Further objects of the present invention are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities as will later more fully appear and are inherently possessed thereby.